Horse Gaits: Sound Doesn't Equal Symmetrical

The team found significant differences between these angles in the sound horses' inner and outer legs when longed in one direction.

Photo: Mallory Haigh/The Horse

A sound horse is one that doesn't limp or drag his feet, but it's by no means a horse that moves symmetrically. Results from new three-dimensional (3-D) studies of the angular motions of horses' legs suggest that most horses' movements differ depending on the direction they travel on a circle, according to a Dutch equitation scientist.

"In equestrian sports, symmetry is an important part of training," said Lotte Hardeman, PhD candidate and researcher in the equine sciences department at Utrecht University. "This is especially true for dressage horses because we expect our dressage horses to perform forward and lateral movements symmetrically to the left and to the right."

But previous research led Hardeman and colleagues to suspect that sound horses did not necessarily move symmetrically. To test their theory, the team used 3-D technology to study the precise variations of angles in horses' legs during straight and circular movement, Hardeman said during her presentation at the 2011 International Society for Equitation Science Conference, held Oct. 26-29 in Hooge Mierde, The Netherlands.

Hardeman and her colleagues evaluated the angles horses' cannon bones create while walking and trotting straight and in circles and on soft and hard ground. For each leg, the researchers measured the angle of front-to-back movement of the bone (the "segmental" angle) and the side-to-side movement of the bone (the "coronal" angle).

The team found significant differences between these angles in the horses' inner and outer legs when longed in one direction, and then found that those angle differences did not exist to the same degree (or existed to a more pronounced degree) when the horse moved in the opposite direction on the circle. Generally speaking, differences between inner and outer legs were more obvious in clockwise circles than in counterclockwise circles, she said.

This asymmetry, Hardeman said, could be caused by "motor laterality"--meaning that the horse behaves asymmetrically. He might, for example, always prefer to put the left leg in front of the right leg.

"We already know that there is a relationship between motor laterality and unevenness of the feet," Hardeman said. "Lateralized behavior might also influence the ability to perform symmetrically."

Researchers have even noted that foals can show motor laterality by always putting, for example, the left front leg in front of the right while grazing, she added. "It has already been proven that these foals develop uneven feet with, in this case, a weak left hoof and a steep right hoof," she said. "We think that if foals are grazing on pasture like this, always around their left forelimb, then that horse will bend more easily to the left than to the right.

Hardeman concluded that, even in sound horses, the locomotion patterns are influenced by the direction the animal travels on a circle. Additonally, she noted that "the absolute segmental and coronal angles seem to be influenced by the laterality of the horse; this phenomenon is more apparent on a circle. The causality is still to be examined."

About the Author

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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